One initial concept of continuous passive motion was pioneered by Dr. Vernon Nickel of San Diego in 1960 and by Dr. Robert Salter of Toronto, who demonstrated significant healing of joint cartilage defects in rabbits when continuous passive motion was applied. Dr. Salter's work, which was published in the December 1980 Journal of Bone and Joint Surgery, inspired Dr. Richard Coutts of San Diego to take the concept and apply it to the post operative total need patient. The preliminary results of Dr. Coutts' work were presented at the 1982 Orthopedic Research Society in January of that year and was entitled "The Role of Continuous Passive Motion in the Post-Operative Rehabilitation of the Total Need Patient". A multi-center study currently going on includes nearly every major orthopedic center in the U.S. and this study will be presented at the 1983 AAOS in Anaheim, Calif.
A number of devices have been disclosed in the prior art for the rehabilitation of the lower extremity. In Volume II of Fractures by Charles A. Rockwood, Jr., and David P. Green, a traction method for tibial condylar fractures allowing 90 degrees of knee movement is disclosed on page 1,168. The pictured method is patient operated by pulling on a cord with a pivoted leg support of the knee. The pictured device allows traction to be maintained on the leg.
A motorized continuous passive motion knee exercise device has been disclosed by Sutter Biomedical Inc. of San Diego, Calif. This device consists of a support for the lower limb made up of two main segments, a thigh support and a lower leg support. The segments articulate through a joint at the knee level and are adjustable to fit the patient's lower limb. The apparatus has additional joints or linkages at the hip and ankle which can be positioned on the patient's corresponding joint. The heel of the orthosis is mounted on wheels which run on a lower track, keeping the device aligned and providing stability. A DC motor is used as a power source and has variable speed control. The motor is attached to a lever having an adjustment of from three to twelve inches. A rope is connected to the end of the lever and passes through two overhead pulleys and is then attached to the knee joint of the support frame through a snap ring. As the lever is turned by the motor, the rope is alternately shortened and lengthened flexing and exercising the knee. Since the arc of motion is determined by the length of the rotating lever arm, by adjusting the rope length one can vary the range of motion to a maximum of 120 degrees.
Another motorized leg exercising device is manufactured by Cogemo, Paris, France, and is distributed in the United States by Richards Manufacturing Co., Inc. of Memphis, Tenn. The device includes a base, thigh support, lower leg support, and foot support. The lower leg support is pivotally attached to the thigh support and is mounted on rollers which engage the base. A gear motor assembly is located below the thigh and lower leg supports and is controlled by a remote panel and a patient controlled switch.
While the leg exercise devices disclosed in the prior art have proven useful in the rehabilitation of the lower extremities, these devices suffer from a number of disadvantages. The Sutter device is unduly cumbersome and difficult to set up. While the Cogemo device is relatively self contained and easy to set up, when used on a bed the sheets or coverings are prone to jamming the device.